ABSTRACT Shared decision making (SDM) is a routine recommendation made by many guidelines when medical decisions are preference-sensitive, such as choosing to undergo prostate cancer or breast cancer screening. SDM typically includes provision of a decision aid, ie, an educational tool such as a written information sheet. However, many such tools are only weakly grounded in behavioral science research theory and often disregard knowledge from numeracy and literacy research. Literature on health numeracy is quite clear that many patients struggle to understand a single risk estimate, let alone multiple countervailing estimates. While the average person reads at a 7?8th grade level, decision aids are typically written at a 9th grade or higher reading level. Additionally, while decision aids often ask patients to clarify their values, behavioral science research on affective forecasting has shown that eliciting preferences for unfamiliar health states is challenging and error prone. Further, although theoretical approaches to decision making emphasize verbatim representations and numerical detail, modern approaches, including dual-process theory and fuzzy-trace theory, emphasize understanding the bottom-line ?gist.? We hypothesize that decision aids that involve complex information sharing, along with preference elicitation for numerous unfamiliar health states, place a substantial burden on people that leads to ?information overload,? which hinders the ability to make good decisions. The objective of this proposal is to conduct a series of studies around participants? comprehension of the information presented in cancer screening decision aids and determine how it relates to information overload. Knowing this will inform optimization of SDM delivery and the design of patient decision aids. Dr. Sigrid Carlsson is an Assistant Attending Epidemiologist at Memorial Sloan Kettering Cancer Center, one of the world?s premier cancer centers with a strong cancer research infrastructure. This K22 Transition Career Development Award is a logical progression from the candidate?s prior research in prostate cancer screening, and will allow her to gain additional skills and experience to reach independent investigator status. Through the proposed career development activities, the applicant seeks to complement her medical background and quantitative expertise with skills in qualitative methods, behavioral sciences, and SDM. Dr. Carlsson?s long- term career goal is to become an independent, NIH-funded investigator with a research program committed to improving the practical application of SDM and optimization of risk-stratified approaches to cancer screening. Pursuing this award will give her the skills, experience, and preliminary data needed to submit 2 larger competitive R01 grant applications to 1) develop a cancer screening decision aid that avoids information overload and test its effectiveness on SDM outcomes in a randomized setting, and 2) develop a decision support tool to be integrated in the electronic medical record and test its effectiveness on health outcomes.